In fabrication of semiconductor devices, a plurality of layers (e.g., a polysilicon layer, an oxide layer, a nitride layer, a metal layer, etc.) are formed on a wafer used as a semiconductor substrate. A photoresist layer is coated on the layer. By an exposure process, a pattern formed on a photomask is transcribed onto the photoresist layer. By an etching process, a desirable pattern is then formed on the wafer.
Layers or photoresist remains at the edge of the wafer where these processes are carried out. In this case, if the wafer is held and transported to a different process, the remaining layers are spattered. Since they act as particles to reduce a yield, there is a need for an etching process to remove the remaining layers or photoresist.
Conventionally, a wafer edge is etched by the following manner. Except a wafer edge to be etched, a top surface of a pattern-formed wafer is shielded by a shielding solution or a mask. Thereafter, an etchant is sprayed onto the wafer or the wafer is submerged into a bath in which an etchant is contained. This manner needs steps of shielding a pattern-formed portion by a shielding solution or a mask and removing the shielding solution or the mask. Accordingly, a long work time is required and a large amount of the etchant is consumed.